Trump told CBS's Face the Nation, "You see these guys making these enormous amounts of money, and it's a total and complete joke."

In U.S. political campaigns, Democratic candidates often criticize the wide disparity between the pay of CEOs of big companies and their employees, which can be as much as 350 times greater. But Republicans, often thought to be the party of big business in the United States, rarely attack the salaries of corporate and Wall Street chieftains.

The 69-year-old Trump often brags about his wealth and business success building New York skyscrapers. But he laid the blame for high CEO pay on the executives themselves, who he said put their friends on corporate boards of directors, who in turn approve the big salaries for company leaders.

"It does bug me," Trump said. "It's very hard if you have a free enterprise system to do anything about that. You know, the boards of companies are supposed to (control spending and high pay executive pay), but I know companies very well and the CEO puts in all of his friends."

Trump has taken a populist, anti-Washington message to the top of the 16-candidate Republican field. He said in the coming weeks he would unveil proposals to cut individual and corporate taxes, "but for the hedge fund guys, they are going to be paying up."

The Republican contenders are getting set for Wednesday's next round of debates, with several of the candidates vowing to attack Trump for his shifting views on U.S. health care, abortion and other issues over the years and make the argument that he is not in line with the views of the party's dominant conservative voters.

Republican Party chairman Reince Priebus told CNN's State of the Union on Sunday that "there will probably be more elbows thrown in that debate" than in the first one last month.

Another Republican political novice, former neurosurgeon Ben Carson, has risen to second behind Trump in surveys of Republicans across the U.S.

In an appearance on ABC's This Week, Carson dismissed Trump's recent remark that he did not have enough energy to be president.